Ensure correctness of atomic store ordering

This commit is contained in:
Liam 2022-11-08 22:26:14 -05:00
parent dc520a487d
commit 71c0e20f95
2 changed files with 9 additions and 3 deletions

View File

@ -384,7 +384,8 @@ void KScheduler::SwitchThread(KThread* next_thread) {
void KScheduler::ScheduleImpl() { void KScheduler::ScheduleImpl() {
// First, clear the needs scheduling bool. // First, clear the needs scheduling bool.
m_state.needs_scheduling.store(false, std::memory_order_seq_cst); m_state.needs_scheduling.store(false, std::memory_order_relaxed);
std::atomic_thread_fence(std::memory_order_seq_cst);
// Load the appropriate thread pointers for scheduling. // Load the appropriate thread pointers for scheduling.
KThread* const cur_thread{GetCurrentThreadPointer(kernel)}; KThread* const cur_thread{GetCurrentThreadPointer(kernel)};
@ -400,7 +401,8 @@ void KScheduler::ScheduleImpl() {
// If there aren't, we want to check if the highest priority thread is the same as the current // If there aren't, we want to check if the highest priority thread is the same as the current
// thread. // thread.
if (highest_priority_thread == cur_thread) { if (highest_priority_thread == cur_thread) {
// If they're the same, then we can just return. // If they're the same, then we can just issue a memory barrier and return.
std::atomic_thread_fence(std::memory_order_seq_cst);
return; return;
} }
@ -476,7 +478,8 @@ void KScheduler::ScheduleImplFiber() {
// We failed to successfully do the context switch, and need to retry. // We failed to successfully do the context switch, and need to retry.
// Clear needs_scheduling. // Clear needs_scheduling.
m_state.needs_scheduling.store(false, std::memory_order_seq_cst); m_state.needs_scheduling.store(false, std::memory_order_relaxed);
std::atomic_thread_fence(std::memory_order_seq_cst);
// Refresh the highest priority thread. // Refresh the highest priority thread.
highest_priority_thread = m_state.highest_priority_thread; highest_priority_thread = m_state.highest_priority_thread;

View File

@ -60,6 +60,9 @@ public:
// Release an instance of the lock. // Release an instance of the lock.
if ((--lock_count) == 0) { if ((--lock_count) == 0) {
// Perform a memory barrier here.
std::atomic_thread_fence(std::memory_order_seq_cst);
// We're no longer going to hold the lock. Take note of what cores need scheduling. // We're no longer going to hold the lock. Take note of what cores need scheduling.
const u64 cores_needing_scheduling = const u64 cores_needing_scheduling =
SchedulerType::UpdateHighestPriorityThreads(kernel); SchedulerType::UpdateHighestPriorityThreads(kernel);